ODK central currently has a gap in easy form editing and the official builder app is AFAIK depreciated and not developed any longer.
Of course it is possible to make forms in Excel via XLSforms and upload them, but an easier and collaborative option would be nice to have right in the web-interface.
A quick win for that might be an OnlyOffice integration, which is a fully open-source browser-based office suite with an Excel compatible collaborative spreadsheet editor.
The OnlyOffice Document server has been integrated into several external software already, and it should be relatively easy to do so in ODK Central as well.
Once integrated people with an account on ODK Central could work together in real-time on drafts in a XLSforms compatible online spreadsheet and then export it to ODK Central easily.